Numerous compositions and processes have been employed in the past for the purpose of removing obstructions in the subterranean matrix structure containing oil and gas. Such obstructions can be exemplified by mineral, organic or other deposits in the matrix fractures or channels through which oil or gas flows to a recovering well. Prior methods to remove obstructions included forcing sand or gels into the matrix to break the obstructions or otherwise increase the channels. Other methods involve attacking the obstructions such as by "acidizing" by treatment with acid. Typical of these methods involve the injection of substances through the well to deliver the treating substances. However, such delivery has problems. One problem is that when acidizing, the acid strength is strongest near the well and weakens along the gradient moving away from the well. This is because the acid reacts first with the obstructive material (e.g. calcium carbonate deposits) nearest the well. Accordingly, as the injected treating material moves from the well, it becomes weakened or spent. A result is requisite multiple treatments resulting in over-treatment near the well and under-treatment away from the well. The spent material is typically recovered back through the well between treatments or after a final treatment.
Because such acids are corrosive and dangerous to handle, low concentrations are used. High concentrations, multiple treatments or prolonged treatments can result not only in an undesired heterogeneous result throughout the matrix, but also in attack and damage to the matrix structure, such as on supporting sandstone, with collapse or other problems, and damage to the well, such as casing, connections, etc. There is still needed compositions and methods for enhancing production of oil and gas fields.